Decaffeinated soluble coffee



J. ORNFELT DEGAFFEINATED SOLUBLE COFFEE Filed NOV. 14, 1945 INVENTORATTORNEY June 7, 1949.,

rtamd June 1, 1949 DECAFFEINA'IED SOLUBLE COFFEE John Ornfelt,Morrlstown, N. 1., asslgnor, by meone assignments, to American HomeFoods, Inc. a corporation of Ohio Application November 14, 1945, SerialNo. 628,421

6 Claims. (CI. 99-70) 1 This invention relates to a processfor-producing decaifeinated soluble coffee.

Decaffeinated whole or ground coffee beans have been articles ofcommerce for many years and have met a favorable reception by thosepersons who are fond of coifee as a beverage but are over-susceptible tothe stimulating effects of caffeine.

It is relatively easy to remove substantially all-say 90% or more-of thecaffeine from coffee beans. One difliculty in making an acceptablebduct, however, is met in attempting to retain .atisfactory coffeeflavor. Another dimculty at is an economic one, namely, the largeinestment required for profitable operation; the operation is oneinvolving the processing of large amounts of solid and liquid materialin relatively expensive equipment and must be carried out on, a largescale to show a profit under competitive conditions.

Two types of commercial process have been developed; I call themrespectively the dry" and the "wet process. Both have been appliedexclusively, as far as I know, to green unroasted coffee.

In the dry" process green coffee beans are extracted directly with anorganic solvent, which removes caileine. It has been found practicallyadvantageous to raise the moisture content of the beans before theextraction by steaming to liberate caffeine from caffeine compounds inthe beans and to inhibit the extraction of natural fats and waxes fromthe beans. After the extraction residual solvent is driven off from thebeans and they are dried to their normal moisture content and thenroasted in the usual way.

In the "wet process the green beans are extracted with water whichremoves caffeine and a substantial part of the other water-solubies, theaqueous extract is extracted with a waterimmiscible organic solvent toremove caffeine, the decafieinated extract is reblended with the beans,the beans and aqueous extract are dried to the normal moisture contentof the beans, and the dried mixture is roasted in the usual way.

I have discovered an improved method of decafieinating coffee in whichthe decaffeinating step follows rather than precedes roasting, and whichis especially applicable to the production of decail'einated solublecoifee either in liquid or solid form.

One object of my invention is to provide an economical process fordecail'einating coffee.

Another object of my invention is to provide a decafieinating process inwhich the decafieinating step is applied to an extract of roastedcoifee.

A further object of my invention is to provide a process especiallysuited to the production of soluble decaffeinated coffee.

Additional objects and advantages of my invention will be apparent fromthe following descri tion.

According to my invention I first roast and grind coflee beans in theusual way. I then extract the ground cofl'ee by percolating hot waterthrough it, the water entering the coffee mass at near its boilingpoint. This extraction removes from the ground coffee substantially allthe caffeine and all the desired water-soluble and water-dispersablematerials which give coffee its I beverage value. I carry out theextraction, and a subsequent concentration step if required, in such away as to produce a highly concentrated aqueous extract containingpreferably in the neighborhood of 40-50% solids.

I then extract this aqueous extract with a volatile organicwater-immiscible solvent for caffeine such as benzene, a chlorinatedhydrocarbon such as methylene chloride, dior'trichloroethylene orethylene chloride, or other commercially available water-immisciblecafieine solvent.

I have found that the concentrated aqueous, cofiee extract has a strongtendency to form emulsions with such organic solvents, but that emulsionformation can be avoided by dispersing the aqueous extract in finedroplets in the solvent. I prefer to do this by pumping the aqueousextract under pressure through a fine nozzle into a column of solventand collecting the decaffeinated extract in a layer after passage of thedroplets through the solvent. If the solvent used is specificallylighter than the extract, I introduce the latter at the top of thecolumn; if the solvent is specifically heavier, I introduce the extractat the bottom of the column.

In addition to the avoidance of emulsion formation there is anotheradvantage in dispersing the coffee extract in the solvent instead ofdispersing the solvent in the extract; the dispersed phase moves throughthe column in a relatively short time-say 2-3 minutes-whereas the timeof passage of the continuous phase is much slower. It is an advantage toprocess a relatively unstable material like coffee extract as rapidly aspossible; hence it is advantageously made the dispersed phase in thedecafleination step.

I have further found that for maximum efflciency the column of solventshould be of limited height. The fine droplets of aqueous extract appearto retain their identity while passing through a certain length ofcolumn and then to coalesce to larger droplets, thus reducing thesurface exposed to the solvent. For example, I'

found that when pumping a concentrated aqueous coffee extract containing40-50% solids through a nozzle having an orifice 0.4 mm. in diameterunder 2% atmospheres (40 pounds per square inch) pressure into thebottom of a column of methylene chloride at or slightly" below roomtemperature, a fine cloud of extract droplets rose through the solvent.These appeared to retain their state of fine subdivision for a height of3.5 to 4.5 m. (12 to 15 feet) above the nozzle and then to coalescegradually to larger droplets. Accordingly, when a travel through thesolvent of more than 3.5-4.5 m. is desirable, I prefer to use two ormore columns in series as described below.

In my process I separately withdraw the decafleinated extract andsolvent-caffeine solution from the top and bottom of the extractionvessel. In the case of extraction columns I prefer to do thiscontinuously, but the extraction can also be carried out batchwise.

The decaiieinated extract contains some entrained and dissolved solventwhich must be removed. If the extract is to be sold in the liquid form,I subject it to a steaming or distilling operation to remove solvent,and then adjust it by dilution if necessary to the desiredconcentration. If it is to be sold or used in powered solid form Isubject it to an evaporative drying operation, e. g. in a vacuum drumdrier, and recover the dried solid residue for packaging or use. Ineither case I condense the distillate, separate the solvent and aqueouslayers. as by decantation, and return the solvent to the extractionsystem for reuse.

The solvent withdrawn from the extraction vessel contains the extractedcaffeine in solution. Since caifeine has a relatively high sales valueit is advantageously recovered and purified. for example to U. S. P.grade. One satisfactory way of doing thisis to run the solution to adistillation-recovery unit from which solvent is recovered as anoverhead distillate and returned to the extraction system, and cafleineis recovered as a residue and recrystallized or otherwise purified.

In order to illustrate and further clarify my invention I describe belowspecific embodiments,

which are intended to be illustrative only and not to limit theinvention.

In the accompanying'drawingz- Fig. 1 is a diagrammatic flow sheet of onemethod of making decafi'einated soluble coffee by my invention; and IFig. 2 is a flow sheet of the decaifeinating step carried out in twoseries stages.

According to the illustrated embodiment of my invention I charge thecoffee extractors l with ground roasted coffee and pass hot waterthrough the inlet 2 into the extractors and through them in series untilthe desired extraction of watersolubles has been effected. The wateradvantageously b introduced at a temperature of 88-93 C. (l90-200 F.)and leaves the extractors at 3 at a temperature of 27-32 C. (80-90 F.).

The extract at this point may contain, say,

about 35% solids, in which case I pass it through an evaporativeconcentrator I of conventional type to bring its solids content to40-50%, a concentration which I have found favorable for furtherprocessing. Excess water is removed from the concentrator at I, and theconcentrated extract is removed at l. A pump 1 forces the extractthrough nozzle 3 in the bottom of decaii'einating column 9 under apressure of 2% atmospheres (40 lbsrper sq. in.). The nozzle may be madeof stainless steel and has an aperture 0.4 mm. in diameter. a

The decafleinating column is made of industrial glass tubing 3 m. (26feet) high and is provided with suitable fittings and inlets and outletsas indicated. It is desirable but not essential to provide a coolingjacket (not shown) around column 9 and maintain its temperature at 5-10C. (40-50 E).

Column 9 is filled for the major part of its length with a layer 10 ofmethylene chloride which is specifically heavier than the coffeeextract. A layer ll of the latter collects on top of the solvent, andoverflows into pct '12 whence itis pumped by pipe l3, pump I4 and pipei5 to vacuum drum drier IS. The solid residue from the drum drier, viz.solid soluble decaffeinated coffee, is continuously discharged from thedrier to a bin lGa for packaging, use'or further processing as desired,The vapors from drier I 6 are taken off by pipe IT to condenser 18, andthe condensate run to decanter l9. Suitable vacuumproducing equipment(not shown) is provided. The aqueous layer is withdrawn from thedecanter at and sent to waste or otherwise disposed of. Thesolvent layeris withdrawn at 2| and returned by pump 22 and pipe 23 to solventstoragetank 24 for reuse in the decaifeination.

To provide the column with a supply of methylene chloride the latter isfed to the top of the column at a controlled rate from solventstoragetank 24 through pipe 25. The solvent flows by gravity from the bottom ofthe column to standpipe 26 which is vented at the top at 21 and has anoverflow 28, the height of which determines the height of solvent in thecolumn.

The solvent leaving the ,column is charged with caffeine. To recover thelatter and condition the solvent for reuse, the solvent is led fromoverflow 28 through pipe 29 to evaporator 30. Here the solvent isseparated from the caffeine by distillation, the distillate being ledthrough pipe 3| to condenser 32 whence the condensate is run throughpipe 33 to solvent-storage tank 24.

The caffeine residue left by evaporation of the solvent is removed fromevaporator at 34 and purified at 35 by carbon treatment andrecrystallization from water. Impurities are removed at 36 and thepurified caffeine is withdrawn at 31 for packaging or further treatmentas desired.

Suitable valves, switches and similar control devices are provided forregulating the flow of the various fluids in the system.

The amount of solvent I circulate per unit volume of coflee extract inmy process depends to some extent on the equipment used. In theequipment illustrated in Fig. l, with a single extractive column Icirculate approximately 8 volumes of solvent to each volume of coiIeeextract cireulated and thereby remove 90-97% of the cafleine in theextract; the cafieine amounts ordinarily to about 5% of the extractsolids. For example in approximate round numbers 8000 l. (2000 gal.)methylene chloride circulated countercurrent to 1000 l. (250 gal.)coffee extract containing 600 kg. (1300 lbs.) solids removes 27-28 kg.(-62 lbs.) or more of the 30 kg. (66 lbs.) caffeine ordinarily containedin the solids. About or more of the caffeine removed is observed thatabout half-way up the decaffeinating column there was a tendency, notobservable in the lower half of the column, for the fine droplets ofdispersed coffee extract to coalesce into larger droplets, thus reducingthe liquid-liquid interface and consequently the extraction capacity.Capacity may be maintained throughout the column of solvent by operatingtwo columns 90 and Bi in series as illustrated in Fig. 2. Here thesolvent columns I are preferably each 3.5 to 4.5 m. (12 to 15 feet)high. Solvent from column 9| overflows through pipe 260 to the top ofcolumn 90, and pot l20, pipe I50 and pump 10 are provided to circulatepartially decaffeinated extract under pressure from the top of column 90through nozzle 80 into the bottom of solvent I00 in column 9i. Otherwisethe operation of the process is similar to that previously described.

While continuous operation of my process is believed preferable, thedecaifeination step may be operated batchwise as noted above. Inbatchwise operation I introduce a charge of cooled aqueous coffeeextract into a broad shallow covered extraction vessel (in order toprovide a high surface: volume ratio), and also introduce several timesits volume of methylene chloride. I agitate the charge with a slowlyrotating stirrer (to avoid emulsion formation) until approximateequilibrium between the liquids is reached, stop stirring, allow tosettle, and withdraw the solvent layer. I repeat the extraction in thesame way until the desired degree of decaifeination is effected, andwork up the decaffeinated aqueous coffee extract and the caffeine-ladensolvent substantially as described for the continuous process with thosevariations in procedure obviously necessitated by batch operation.

Other modifications of my process may also be made within the scope ofthe appended claims without departing from my invention.

I claim:

of beverage value, continuously feeding into a column a water-immiscibleorganic solvent for 1. The process of producing soluble decaffein- 90percent by weight of the caffeine has been removed from the aqueousextract, separating the decaffelnated aqueous extract from thecaffeineladen solvent, and freeing of residual organic solvent theaqueous coifee extract decaifeinated by contact with the organic solventto produce soluble decaffeinated coffee.

2. In combination with the process defined in claim 1, the further stepof removing water from the decaffeinated aqueous coffee extract, wherebya residue of solid soluble decaifeinated colfee is obtained.

3. The process of decaffeinating coffee, which comprises extractingground roasted coifee beans with hot water to produce a concentratedaqueous extract containing at least about 40 percent soluble coffeesolids including caffeine and watersoluble and water-dispersible coffeeconstituents caffeine having a specific gravity different from that ofthe aqueous extract, continuously dispersing said aqueous coffee extractat a reduced temperature in the form of fine droplets into the solventin the column at such a point as will permit travel of the droplets bygravity through the major part of the height of the body of solvent andthe formation of a layer of aqueous extract at the end of their travel,whereby caffeine is extracted from the aqueous extract by the solvent,continuously removing decaifeinated aqueous extract from the aqueousextract layer, continuously removing caffeine-laden solvent from the endof the column remote from the aqueous extract layer, and freeing ofresidual solvent aqueous extract decaifeinated by contact with thesolvent.

4; The process of producing solid soluble decaffeinated coffee, whichcomprises forming an aqueous extract of ground roasted coffee beans,said extract containing at least about 40 percent by weight of solublecoffee solids including caffeine and water-soluble and water-dispersiblecoffee constituents of beverage value, continuously feeding methylenechloride into a column to provide a vertically elongated layer thereof,continuously dispersing said aqueous coffee extract in the form of finedroplets into the methylene chloride at a point near the bottom of theelongated layer, whereby the droplets ascend through said elongatedlayer and caffeine is extracted from the droplets by the methlyenechloride, continuously removing at least partially decaifeinated coffeeextract from the top of the elongated methylene chloride'layer,evaporating at low temperature to substantial dryness coffee extractdecaffeinated by contact with the methylene chloride to produce aresidue of solid soluble decaffeinated coffee, separating methylenechloride from the overhead distillate of the evaporation, and reusing itto decaifeinate additional coffee extract.

5. The process of claim 4, in which the decaffeination of the coffeeextract takes place in two series stages in each of which the extractdroplets ascend through at least about 3.5 m. and not more than about4.5 m. of methylene chloride and in which coffee extract and methylenechloride are passed countercurrent to each other from stage to stage.

6. The process of claim 4, in which the volume ratio of methylenechloride circulated to coffee extract circulated is not less than about6:1, whereby not less than about percent of the original caffeinecontent of the coffee extract is removed:

JOHN ORNFELT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Patent No. 2,472,121.

June 7, 1949.

Column 3, line surface: volume read methylene;

and that the said Letters Patent should be read With th e same mayconform to ese corrections therein that the record of the case in thePatent Oifice. Signed and sealed this 1st day of November, A. D. 1949.

32, for the word powered r ead powdered; 0 read swjacewolum olumn 5,line 31, for e; column 6, line 34, claim 4, for methlyene THOMAS F.MURPHY,

Assistant Commissioner of Patents,

